Emma Saylor got a frantic call from her mother last January that her 26-year-old brother Ethan had been rushed to the hospital after a confrontation with Frederick County, Md., off-duty sheriff's officers at a movie theater showing of "Zero Dark Thirty."

Ethan, who had Down syndrome, enjoyed the film so much that he decided to go back to his seat for a second showing while his aide went to get the car to take them home. When he refused to buy another $12 ticket, off-duty police moonlighting as security guards allegedly tackled him in an attempt to eject him from his seat.

The case went to a grand jury, which declined to indict the three sheriff's officers involved in the Jan. 12 incident, according to the Washington Post.

And now Saylor, 23, wants some answers about what happened to her older brother. "It was unreal," said Saylor, who works in affiliate relations for the National Down Syndrome Society.

"It's not clear what happened exactly and that's where our questions are coming from," she said. "All we know is he ended up dead. No one expects their brother to go to a movie and not come home."

Saylor said when the mall officers pulled Ethan from his seat he panicked and then screamed for his mother.

When the aide, whom Saylor would not identify, returned to witness the police asking Ethan to buy a ticket or leave, she told them he didn't like to be touched and would "freak out." The family alleges officers ignored her pleas as Ethan was handcuffed and dropped to the floor, then stopped breathing.

Saylor said the aide was "too upset" to make much sense of what was happening.

When ABCNews.com asked Sheriff Chuck Jenkins for the police report on the incident, which was made public in July, he referred all requests to the agency's lawyer, Daniel Karp. However, Karp was in court at press time and could not return calls for comment.

Now, Saylor has filed a petition on change.org calling for a new investigation and better law enforcement training, which has garnered more than 207,000 signatures. She has also asked the Maryland attorney general and governor to reopen the case.

The National Down Syndrome Society has asked the Justice Department to investigate whether Ethan's rights were violated under the Americans With Disabilities Act. A Department of Justice spokesperson would only confirm that they are "reviewing" the case.

Saylor says her brother, at 5-foot-6 and 294 pounds, was "overweight" and the Chief Medical Examiner Office in Baltimore indicated that may have contributed to the asphyxiation. The medical examiner also noted damage to Ethan's larynx that may have contributed to his death, according to numerous press reports.

"The manner of death was determined to be homicide," said Bruce Goldfarb, assistant to the chief ME. "It was complicated by Down syndrome, atherosclerotic disease and some cardiac abnormalities."

After living independently in an apartment, Ethan had decided to return to live in an in-law apartment at his family's home in Frederick with his parents, sister and 21-year-old brother Adam.

Saylor said her brother had a sunny disposition.

"He was always making us laugh and doing something goofy," she said. "Often we would drive to the mountains and do something special together. He was very funny and could lighten any mood in any situation."

Police indicated that Ethan had been belligerent, according to reports in the Washington Post. But Saylor said that was not typical of adults with Down syndrome or her brother.